Table 1.

Mutants Defective in ABA Synthesis or Response

SpeciesMutationSelection/ScreenPhenotypeAlleles or
 OrthologsGene productReferences
Arabidopsisaba1Suppressors of non-germinating GA-deficient linesABA deficient; wilty; decreased stress or ABA induction of gene expression; sugar-resistant seedling growthlos6
 npq2Zeaxanthin epoxidaseKoornneef et al., 1982; Ishitani et al., 1997; Niyogi et al. 1998; Xiong et al., 2001b
aba2Reduced dormancyABA deficient; wilty; decreased stress or ABA induction of gene expression; sugar-resistant seedling growthgin1
 isi4
 sis4Leon-Kloosterziel et al., 1996; Laby et al., 2000; Rook et al., 2001
aba3Reduced dormancyABA deficient; wilty; decreased stress or ABA induction of gene expression; freezing sensitive; sugar-resistant seedling growthfrs1
 los5Aldehyde oxidase MocoLeon-Kloosterziel et al., 1996; Ishitani et al., 1997; Llorente et al., 2000; Rook et al., 2001; Xiong et al., 2001c
aao3Wilty phenotypeABA-deficient leaves; wilty, but near-normal seed dormancyTomato
 sitiens?Aldehyde oxidaseSeo et al., 2000
abi1-1ABA-resistant germinationNondormant seed; pleiotropic defects in vegetative ABA responseProtein phosphatase 2CKoornneef et al., 1984; Leung et al., 1994; Meyer et al., 1994
abi2-1ABA-resistant germinationSimilar to abi1-1Protein phosphatase 2CKoornneef et al., 1984; Leung et al., 1997; Rodriguez et al., 1998
abi3ABA-resistant germinationPleiotropic defects in seed maturation; vegetative effects on plastid differentiationCereal
 VP1 B3 domain transcription factorKoornneef et al., 1984; Giraudat et al., 1992
abi4ABA-resistant germinationSugar- and salt-resistant germination and seedling growthgin6
 isi3
 san5
 sis5
 sun6APETALA2 domain transcription factorFinkelstein, 1994; Finkelstein et al., 1998; Arenas-Huertero et al., 2000; Huijser et al., 2000; Laby et al., 2000; Rook et al., 2001
abi5ABA-resistant germinationSlightly sugar-resistant germination and seedling growthAtDPBF1bZIP domain transcription
 factorFinkelstein, 1994; Finkelstein and Lynch, 2000a; Lopez-Molina and Chua, 2000
abi8ABA-resistant germinationStunted growth, defective stomatal regulation; male sterileFinkelstein and Lynch, 1997
abh1ABA-hypersensitive germination and guard cell responsePleiotropic; also enhanced drought tolerancemRNA CAP binding proteinHugouvieux et al., 2001
era1Enhanced response to ABA at germinationEnhanced stomatal response/drought tolerance, meristem defectwiggumFarnesyl transferase,
 β-subunitCutler et al., 1996
era3Enhanced response to ABA at germinationAllelic to ein2; ethylene insensitiveein2Membrane-bound metal sensor?Alonso et al., 1999; Ghassemian et al., 2000
ctr1Enhance ABA resistance of abi1-1Reduced dormancy, constitutive triple response to ethyleneProtein kinase
 (Raf family)Kieber et al., 1993; Beaudoin et al., 2000
gca1
 gca2ABA-resistant
 root growthPleiotropic effects on growth, stomatal regulation, and germinationHimmelbach et al., 1998; Pei et al., 2000
gca3-gca8ABA-resistant
 root growthHimmelbach et al., 1998
ade1Deregulation of KIN2:: LUC expressionNo growth phenotypeFoster and Chua, 1999
hlq
 sbrAberrant patterns
 of Dc3::GUS
 expressionPleiotropic, seedling lethalRock, 2000; Subramanian et al., 2002
hos1Hypersensitive to osmotic stress induction of RD29::LUCHypersensitive to ABA-induced gene expressionRING finger
 protein(Ishitani et al., 1997; Lee et al., 2001
hos2
 hos5Hypersensitive to osmotic stress induction of RD29::LUCHypersensitive to ABA-induced gene expressionIshitani et al., 1997; Xiong et al., 1999
sad1Supersensitive to ABA and drought induction of RD29::LUCReduced ABA biosynthesis, hypersensitive to ABA inhibition of germination and root growthU6-related
 Sm-like small ribonucleopro-
 teinXiong et al., 2001a
cla1Chloroplasts alteredABA deficient1-Deoxy-d-xylulose-5-phosphate synthaseEstévez et al., 2001
hyl1Hyponastic leavesHypersensitive to ABADouble-stranded RNA binding proteinLu and Fedoroff, 2000
axr2Auxin-resistant root growthResistant to ABA and ethylene; dominant negativeIAA7 transcription regulationWilson et al., 1990; Nagpal et al., 2000
bri1Brassinosteroid insensitiveABA hypersensitiveSer/Thr protein kinaseLi and Chory, 1997; Steber and McCourt, 2001
det2De-etiolatedABA hypersensitiveSteroid reductaseSteber and McCourt, 2001
fry1Constitutive expression of RD29::LUCABA hypersensitiveInositol polyphos-phate-1-phos-phataseXiong et al., 2001b
jar1
 jin4Jasmonic acid resistantHypersensitive to ABA-inhibition of germinationStaswick et al., 1992; Berger et al., 1996
lec1Leafy cotyledons, seed lethalSlightly ABA-resistant germinationCCAAT-box binding, HAP3 homologMeinke et al., 1994; Parcy et al., 1997; Lotan et al., 1998
los1Low sensitivity to osmotic stress induction of RD29::LUCLow sensitivity to ABA induction of gene expression
prl1Hypersensitivity to Glc and SucHypersensitive to ABA (also to cytokinin, ethylene, and auxin)Nuclear WD40 domain proteinNémeth et al., 1998; Bhalerao et al., 1999
sax1Hypersensitive to auxinABA hypersensitive, BR deficientEphritikhine et al., 1999
uvs66UV light sensitivityHypersensitive to ABA inhibition of root growthAlbinsky et al., 1999
Resurrection
 plantcdt-1ABA-independent desiccation toleranceConstitutive ABA response in callus culturesRegulatory RNA or small peptideFurini et al., 1997
BarleycoolDecreased leaf temperatureABA insensitivity in guard cellsRaskin and Ladyman, 1988
Maizevp1ViviparousABA-insensitive seedsABI3B3-domain transcription factorRobertson, 1955; McCarty et al., 1991
vp2-
 vp14ViviparousABA deficientRobertson, 1955; Neill et al., 1986; Schwartz et al., 1997
reaDefective
 germinationRed embryonic axis caused by anthocyanins; ABA-resistant germination; occasional viviparySturaro et al., 1996